In the field of ophthalmology, solubilizing agents are added to a variety of preparations. In particular, various solubilizing agents are added to aqueous ophthalmic compositions to help dissolution of biologically active components and additives with relatively low water solubility, and the like. One example of solubilizing agents used in the field of ophthalmology is a surfactant. An aqueous formulation containing a surfactant is known to foam easily, and foam is generated when subjected to vibration or impact during production or distribution.
In general, to use an aqueous ophthalmic composition in a manner safe on the eyes, the dissolution check during production is considered important. Of aqueous ophthalmic compositions, medical products such as eye drops and eye washes require foreign matter detection in the production steps. However, when foam is generated in the aqueous ophthalmic composition during production, and disappears at a low speed, the foam is difficult to distinguish from active ingredients and foreign matter. Consequently, dissolution check and foreign matter detection take a long period of time, preventing efficient production.
Terpenoid is sometimes added to an ophthalmic composition to provide a cooling sensation during application (see Patent Literature 1). Unfortunately, when an ophthalmic composition containing terpenoid is stored in a container, the terpenoid concentration is known to be reduced with time. This is presumably because of adsorption of terpenoid on the container, volatilization of terpenoid, or the like; however, an effective solution to this problem has not been found.